(a) Field of the Invention
The present invention relates to a protection switching method and apparatus.
(b) Description of the Related Art
Protection switching is a method of restarting traffic to the highest degree when the traffic is stopped due to the generation of a failure in a network. A protection switching method is classified into linear protection switching, ring protection switching, and shared mesh protection switching according to the topology of a network. The linear protection switching includes various protection architectures, such as 1+1, 1:1, 1:N, and M:N.
In protection switching, paths between nodes are basically divided into a working path and a protection path. When there is no failure, traffic is carried along the working path. When a failure occurs in a network or a path is changed by control of an operator, the traffic is carried along the protection path.
Standardization for shared mesh protection switching has recently been under progress. The shared mesh protection switching is a method in which protection paths for protecting a working path between different terminals share limited resources, and is used to improve use efficiency of network resources. In this method, since protection paths allocated for different working paths share limited resources, only a protection path allocated for a working path having high priority can perform switching for traffic using shared resources when a failure is generated in different working paths at the same time. Here, assuming that only one protection path is provided to different working paths, if a working path having high priority uses the protection path due to its failure, the failure of a working path having low priority is not protected.
A working path having low priority can use an m:1 protection architecture so that it can switch traffic to another protection path. That is, protection switching can be performed using an available path, from among m protection paths, by allocating the m protection paths in order to protect one working path.
Meanwhile, in transport networks, such as Ethernet, a Multi-Protocol Label Switching—Transport Profile (MPLS-TP), and an Optical Transport Network (OTN), a 1+1, 1:1, or 1:n protection architecture is used for linear protection switching. The protection architectures have a common point in that they use only one protection path in order to protect one or n working paths.
Accordingly, since only one protection path that can be used when a protection switching situation is generated is present, the allocation of a plurality of protection paths, such as an m:n or m:1 protection architecture, is considered in any Automatic Protection Switching (APS) protocol defined so far.